In the manufacture of decorative sheet-type covering material, such as sheet vinyl floor coverings, normal manufacturing procedure calls for coating the substrate, such as felt backing, with various plastic layers. The substrate used is typically a substrate such as felt with relatively low pore volume and the felt is frequently primed or sealed to make a suitable substrate for application of decorative and functional plastic layers. The felt used is typically an asbestos felt. Because of various hazards involved in the use of asbestos it is desirable to utilize other materials as the substrates for decorative sheet type covering materials. One of the suggested substrates is fiberglass in the form of fiberglass mats which frequently have relatively large void volumes such as on the order of 98% or more. In order to use such materials satisfactorily it is desirable to fully incapsulate the fibers of the mat or web so as to minimize glass fiber irritation during processing and installation.
It has been suggested as set forth for instance in U.S. Pat. No. 4,041,197 to coat relatively open substrates such as cotton scrim or nylon scrim with liquid plastic by first applying the plastic to the web of scrim and then passing the coated substrate between a put-on roll and a heat drum to smooth and compress the plastic coating onto the web. A similar coating operation is described in U.S. Pat. No. 3,519,460 for use on fibrous webs such as paper or felt.